1. Field of the Invention
The invention relates to a telescoping arm gate opening and closing apparatus having a threaded rod actuator that is driven in rotation clockwise and counter-clockwise to respectively retract and extend the arm.
2. Background Art
The inconvenience of manually opening and closing a gate has long been recognized. In response, numerous gate openers have been designed that automatically open and close a gate. Examples of prior art gate openers are disclosed in U.S. Pat. Nos. 3,500,585; 4,330,958; 4,403,449; and 4,416,085. None of the prior art devices present a design that is reliable and efficient in operation; inexpensive to manufacture; easy to install; and simple to maintain.
For example, U.S. Pat. No. 3,500,585 discloses a reciprocating ram gate opener having a mechanically complex spring loaded latch mechanism that must be unlatched before the gate can be opened. Thereafter, the entire length of the ram passes through the power unit so that it extends out to the other side of the unit. Since the ram extends from the power unit to the mid-portion of the gate, the length of the ram is quite long. Passing the long ram through the power unit is inefficient and requires the availability of a commercial source of power to be operated in an economically practical manner. The ram is also cantilever supported from the power unit while the gate is open. This subjects the ram to bending stresses that can eventually cause the ram to bend and the opener to fail in operation.
In the other mentioned U.S. patents, the need for a mechanism to unlatch the gate has been obviated, but the openers include articulated lever actuators that are undesireable. It is inefficient to open a gate by applying a torque to one lever that is pivotally connected to a second lever, which is attached to the gate. This problem is apparent from an analysis of the gate openers disclosed in U.S. Pat. Nos. 4,403,449 and 4,416,085. In each of these patents, a first lever is pivotally mounted at one end for rotation about a vertical axis. In U.S. Pat. No. 4,403,449, a torque is applied to rotate the first lever by a driven gear that is fixed to the lever at the pivot point. This results in an inefficiency created by applying a torque to the lever through a very short moment arm equal to the radius of the driven gear. The latter patent attempts to solve this inefficiency by applying a torque to the pivotally mounted first lever by a reciprocating ram spaced a distance away from the pivot point. This establishes a moment arm of increased length which results in decreasing the work required to rotate the lever, but the mechanical complexity of the opener is increased as a result. Whereas U.S. Pat. No. 4,403,449 requires a motor driven transmission to directly drive a gear driven first lever, the latter patent requires a motor to power a bi-directional gear pump that operates a hydraulically driven ram coupled to the gear pump through hydraulic lines. Therefore, neither of these patents discloses a satisfactorily designed gate opener having a minimum power requirement achieved through a simple and practical mechanical design.
The need exists to provide a gate opening apparatus having a minimum power requirement for operation that does not require a latching mechanism, and that moreover is dependable in operation, inexpensive to manufacture, and simple to install and maintain. Gates are not always located in areas that are accessible to commercially generated power. In these areas gates are provided with battery powered openers. Since all electrically powered openers drain the battery to which they are connected, the battery must be periodically charged. Solar cell panels have been provided to charge the batteries, but the greater the power drain on the battery, the larger the solar cell panel needs to be in order to maintain the battery fully charged. Since solar cell panels are one of the most expensive items in a battery powered gate opener, it is important that the gate opener be designed to use a minimum of power so that the smallest and least expensive solar cell panel can be used to charge the battery. It is also important that the gate opener be constructed from components that are inexpensive and readily manufactured so that it is economically practical to use the gate opener in areas not serviced by commercially generated power.